The present invention relates to a light detection equipment in components with optical access.
One of the operating ranges of the light detection equipment is that of the control of industrial components formed by a hermetically closed metallic envelope, which have one or more optical accesses for the inspection and contains devices of different nature. In the electric case, said industrial component may be, for example, a sheathed conductor that is formed by a medium or high voltage conductor that is enclosed in a metallic pipe representing the envelope, or by a current/voltage transformer that is enclosed in a hermetic metallic chamber. The space among above-mentioned devices and the internal walls of the envelope where such devices are located can be empty or filled up with fluids, even in pressure, which are transparent to the light and which insulate totally such devices as, for example, the sulphur hexafluoride in sheathed conductors and the oil in transformers.
Since the defects that said industrial components show, which are due for example to material ageing phenomena or to imperfection presence or to dirt, a degradation of the electric industrial component insulation happens which is correlated with light phenomena, even of minimum intensity (at least at the beginning). Such light phenomena which are an index of damage in the same industrial component, must be detected so that a phenomenon identification can be obtained and also, when it is necessary, a repair or replacement of the industrial component can be made.
The light intensity that arrives at the internal surfaces of the containment envelope can change from 10xe2x88x9216 Watt/cm2 to 10xe2x88x929 Watt/cm2; according to that, the technology used for the emitted light detection can change from photon count to analog detection measured continuously).
The light intensity that arrives at the internal surfaces of the containment envelope can change from 10xe2x88x9216 Watt/cm2 to 10xe2x88x929 Watt/cm2; according to that, the technology used for the emitted light detection can change from photon count to analog detection (measure in continue).
The main features that a detection device of such type must have are:
high sensibility of luminous phenomenon detection
high signal/noise ratio
rapidity of measure (maximum measure times in the order of the minute)
immunity to electromagnetic interferences and mechanical troubles (for example vibrations)
modularity of the system
remote control of the optical probe
compactness of the optical probe
simplex installation of the optical probe in the optical access
simplex use of the system
Presently three different types of equipment for light radiation detection in industrial components with optical access are essentially known.
A first equipment uses an optical fiber with large diameter of nucleus (usually an optical fiber with a liquid nucleus of 4.5 mm in diameter), which faces on the optical access window and carries the light arriving from inside the component to the sensitive area of a photomultiplier tube located to about two meters from the component. The optical fiber is not very efficient to collect the light from all the angles (usually it shows a good efficiency only on acceptance angles that do not overcome +/xe2x88x9234xc2x0 with respect to its optical axis), therefore a special joint must be used that orients the optical fiber according a prefixed angle with respect to a predetermined axis. The electric signal arriving from the photomultiplier tube is subsequently processed in order to obtain the information deriving from the light radiation intensity.
A second equipment uses a photomultiplier tube directly faced to the optical access window in order to detect the light arriving from inside the component. The electric signal arriving from the photomultiplier tube is subsequently processed in order to obtain the information deriving from the light radiation intensity.
A third equipment uses a cylindrical light conveyor, which ends with a concave conical surface, which penetrates into the component and collects the light arriving from 0xc2x0 and 90xc2x0 angles with respect to the axis of the same conveyor. The light emerges from the light conveyor and is conveyed in an optical fiber beam arriving at a sensor (for example a photodiode).
The first equipment requires the presence of an operator to orient the joint and therefore requires very long measure times, often not compatible with the measure type that must be effected. Also, if the length of the optical fiber used overcomes two meters and the light source emits mainly in a radiation field next to UV band, a notable attenuation of the collected light happens. At the end such equipment shows a so high cost that is not possible to use this equipment in industrial scale.
The second equipment shows a minor efficiency because the photomultiplier tube is placed outside the optical access window, and this allows a notable reduction of the light collecting angles.
The third equipment does not allow to collect the light sinking the cylindrical element at angles that are significantly different from 0xc2x0 and 90xc2x0. Also such equipment does not convey the light in the optical fiber beam in efficient way.
In view of the state of the art described, it is an object of the present invention to show a light detection equipment that allows to detect the light arriving from any angles and which has a very high sensitivity, even at very low luminous intensity levels, allowing very fast measure times.
According to the present invention, such object is attained by a light detection equipment in a component with at least one optical access, characterized by comprising light conveyor means having a first terminal part faced inside said component through said optical access, said first terminal part being formed by a spherical cap collecting the light arriving from any angle inside said component, said light conveyor means having a second terminal part with a surface faced and substantially in contact with a sensitive element of an optical transducer.
Thanks to the present invention it is possible to form an equipment for light detection in components with optical access that allows to detect the light arriving from any angle and to minimize the measure times by a very high sensitivity, even at very low luminous intensity levels, and which also shows reduced size to allow its use in industrial structures.